Magnetically-suspended armature



c. F. JENKINS MAGNETICALLY SUSPENDED ARMATURE Filed Dec. 18, 1922 Patented Feb. 10, 1925.

UNITED STATES PATENT "OFFICE.

CHARLES FRANCIS JENKINS, OF WASHINGTON, DISTRICT OF COLUMBIA, ASSIGNOR TO RADIO PICTURES CORPORATION, OF WASHINGTON, DISTRICT OF COLUMBIA, A.

CORPORATION.

MAGNETICALLY-SUSPENDED ARMATURE.

Application filed December 18, 1922. Serial No. 607,613.

To all whom it may concern:

Be it known that I, CI-IARLl-IS FRANCIS JENKINS, citizen of the United States, residing at \Vashington,-District of Columbia, have invented certain new and useful Improvements in a MagneticallySuspended Armature, of which the following is a specification.

g This invention relates to apparatus for the broadcasting of radiopictures, and has for its principal object to provide means for impressing on a photographic plate a light of varying intensity, by means of devices hereinafter described, and particularly pointed out in the claims.

In the accon'ipanying drawings Fig. 1 is a top view of the device, and Figs. 2, 3 and 4 details thereof, in which A is a lamp enclosing as a light source a ribbon filament A, B a lens for converging the light from the source onto a. mirror C (Fig. 4:) and reflected therefrom onto a disc D having an aperture E therein, the lamp A. has an opaque strip A vertically across its face. This opaque strip is imaged across the disc D as a shadow E in such a location and width .as'to cover the'aperture E in the disc.

The mirror C is mounted on a rotatable shaft F having also mounted thereon an iron armature G. The shaft F is pivoted in a frame II which maintains the shaft vertically in the magnetic field of the permanent magnet I, upon the poles of which are mounted pole-pieces I,the' effect of wl'iich is to concentrate the magnetic stream upon the armature G, holding same in parallel align ment therewith. There are four electro-magnets K, K, K, K, arranged in pairs with their polar-alignment crossing at right angles. These poles are equi-spaced around the shaft F, and are connected in series to the binding posts M and M. The wind- .ings in the electro-magnets are such as to concentrate the magnetic flux therefrom acrossthe shaft F, with the plus (-1-) poles on one side of the magnetic stream of the permanent magnet I, and the minus poles on the other side of the stream.

The. operation of the device, therefor, is as follows The lamp being lighted the light therefrom is reflected from the mirror (3 onto the disc D in two semi-discs, that is, with a shadow between the boundary lines of which are indicated by solid lines, the boundary of the light beam by dotted lines. This shadow lies over the opening E in the disc I) so that no light passes through the aper ture. If, however, the shaft F should rotate more or less, the mirror C would correspondingly vibrate, which would cause the shadow to vibrate across the aperture from side to side.

Said vibration of the shadow would permit light to pass through the opening in volume proportionate to the amplitude of vibration of the shadow. That is, if the shadow onlyvibrates through a small amplitude the aperture would be uncovered only in part, and, therefore, the light passing therethiough would be small. On the other hand, if the amplitude of vibration of the shadow is maximum, then the maximum of light would pass through the aperture, and likewise for any degree of amplitude the amount of light passing through the aperture is. in exact proportion thereto.

The vibration of the mirror is directly a result of the 'ibration'of the armature G caused by pulsating, 01 preferably an alter nating current, in the electro-111agnets K, K,

K, K, a phenn'nena well understood. As the oscillation of the armature G is directly pro? portional to the strength of the current in the solenoids, it is evident that the vibration of the shadow is also proportionate to the current strength; and as the amplitude of rib ation of the shadow I l is proportionate to the strength of the current, itis likewise obvious that the amount of light passing through the aperture E is directly proportionate to the current strength coming to the electro-magnets.

As the application of the light after it passes the aperture E not pertinent to the discussion of the invention the subject of this application, to follow the lightfarther is probably not necessary.

l Vhat I claim, therefore, as my invention, and wish to secure by United States Let ters Patent, is

1. In apparatus of the class described, an iron armature in a uni-directional. i'uagnetic stream held approximately longitudinal therewith by said stream, means for producing said magnetic field and a second magnetic field controllable in strength located to effect a displacement of said armature.

2. 'In apparatus of the class described, a vibrating iron armature in a magnetic field held approximately longitudinal therewith by said stream, means for producing said magnetic field, a source of light, and means in conjunction with said light for producing a shadow, and means whereby said armature vibrates said shadow approximately in proportion to an electric current acting on said armature.

3. In apparatus of the class described, a source of light, a mask for producing a shadow in one direction from said light, an iron armature in a magnetic field, means for producing said magnetic field, means for impressing a second variable magnetic field on said armature, a mirror so mounted that movement of the armature vibrates said mirror to give a vibration effect to the shadow from the lamp reflected from said mirror.

In testimony whereof I have aflixed my signature.

CHARLES FRANCIS JENKINS. 

